Site News  |   Monitor Keywords  |   Monitor Archive  |   Organizer  |   Account Info  |

Information processing apparatus, information processing method, program for executing the information processing method, storage medium storing the program, dma controller, dma transfer method, program for executing the dma transfer method, and storage m

Information processing apparatus, information processing method, program for executing the information processing method, storage medium storing the program, dma controller, dma transfer method, program for executing the dma transfer method, and storage m description/claims

The present invention contains subject matter related to Japanese Patent Application JP 2007-211860, filed in the Japan Patent Office on Aug. 15, 2007, the entire contents of which being incorporated herein by reference.

1. Field of the Invention

The present invention relates to an information processing apparatus and an information processing method for direct memory access (DMA) transferring information between a storage section in an information transfer system, such as a network card, and a storage section in an information processing system having a microprocessor (CPU), a program for executing the information processing method, a storage medium storing the program, a DMA controller, a DMA transfer method, a program for executing the DMA transfer method, and a storage medium storing the program. Specifically, descriptor information concerning the DMA transferred information is DMA transferred from a second storage section in the information transfer system to a first storage section in the information processing system, and the DMA transferred descriptor information is loaded from the first storage section. Thus, the descriptor information can be loaded without the need to access the second storage section in the information transfer system, which would require a long processing time, and a processing speed of the apparatus can be increased.

2. Description of the Related Art

In recent years, DMA transfer has been widely employed in order to allow information to be transferred between the storage section in the information processing system and the storage section in the information transfer system at a high speed. For example, a descriptor is stored beforehand in a register of a DMA controller in the information transfer system, e.g., the network card, and the CPU writes, to the register of the DMA controller, an address of a destination (or a source) and an amount of data to be transferred. Thereafter, the CPU issues a start command to the DMA controller, thereby initiating a DMA transfer. When the transfer of that amount of data, which has been written to the register, is complete, this transfer operation is completed. Thus, operation information such as the destination address and so on needs to be written to the register each time a transfer operation is performed, and this burdens the CPU.

By way of addressing this problem, the CPU may generate, on a random access memory (RAM), a descriptor (a DMA transfer information queue) indicating the destination address and so on, and instruct the DMA controller to start the DMA transfer. Upon receipt of the instruction to start the DMA transfer from the CPU, the DMA controller performs the DMA transfer while referring to the descriptor generated on the RAM. Thus, the CPU is capable of issuing an instruction to start data transfer asynchronously to the DMA transfer. This enables high-speed processing, in particular when a plurality of pieces of data are DMA transferred.

When the DMA transfer is complete, the DMA controller provides an interrupt to the CPU. Upon receipt of the interrupt, the CPU loads the descriptor from the register of the DMA controller. After loading the descriptor, the CPU performs a process of releasing a buffer and so on in the case where the DMA transfer completed is sequential transmission, and processes received data in the case where the DMA transfer is data reception.

In connection with the above related-art technique, Japanese Patent Laid-open No. 2002-140286 (page 6, FIGS. 3 and 5) discloses an information processing apparatus having a DMA transfer capability. In this information processing apparatus, a DMA controller 41 loads descriptor information 53 stored in an image memory 43 into a register prepared in the DMA controller 41. As a result, the DMA controller 41 is able to perform a DMA transfer process while referring to the loaded descriptor information 53.

Notice here that, in the case of the DMA controllers according to the related-art technique and Japanese Patent Laid-open 2002-140286, the CPU, upon receipt of the interrupt provided when the DMA transfer is complete, loads the descriptor by referring to the register of the DMA controller. This process of the CPU loading the descriptor from the register of the DMA controller, however, is slower than a process of the CPU accessing the RAM, for example. This is because the CPU needs to use a special command to access the register of the DMA controller, since a memory space in the register of the DMA controller is distinct from a memory space of the RAM, for example.

The present invention addresses the above-identified, and other problems associated with existing methods and apparatuses, and provides an information processing apparatus and an information processing method that enable high-speed processing while allowing the descriptor information to be loaded without the need to access the storage section in the information transfer system, which would require a long processing time, and also provides a program for executing the information processing method, a storage medium storing the program, a DMA controller, a DMA transfer method, a program for executing the DMA transfer method, and a storage medium storing the program.

According to one embodiment of the present invention, there is provided an information processing apparatus that transfers information, using DMA, between a first storage section in an information processing system and a second storage section in an information transfer system, the information processing system including the first storage section configured to store the information, and a control section configured to control the apparatus, the information transfer system including the second storage section configured to store descriptor information that indicates a location at which the information is stored in the first storage section and a size of the information, and a DMA transfer section configured to DMA transfer the information between the first storage section and the second storage section based on the descriptor information stored in the second storage section, wherein the DMA transfer section DMA transfers the descriptor information concerning the DMA transferred information from the second storage section to the first storage section, and the control section loads, from the first storage section, the descriptor information which has been DMA transferred by the DMA transfer section.

According to the above-described information processing apparatus, when the information is DMA transferred between the first storage section in the information processing system and the second storage section in the information transfer system, the descriptor information that indicates the location at which the information is stored in the first storage section and the size of the information is stored in the second storage section. Based on the descriptor information stored in the second storage section, the DMA transfer section DMA transfers the information between the first storage section and the second storage section. In this case, the DMA transfer section DMA transfers the descriptor information concerning the DMA transferred information from the second storage section to the first storage section. At this time, the control section loads, from the first storage section, the descriptor information which has been DMA transferred by the DMA transfer section. Thus, the control section is capable of loading the descriptor information without the need to access the second storage section in the information transfer system, which would require a long processing time.

According to another embodiment of the present invention, there is provided an information processing method of DMA transferring information between a first storage section in an information processing system and a second storage section in an information transfer system. The method includes the steps of: generating descriptor information that indicates a location at which the information is stored in the first storage section and a size of the information; storing the generated descriptor information in the second storage section in the information transfer system; DMA transferring the information between the first storage section and the second storage section based on the descriptor information stored in the second storage section; DMA transferring the descriptor information concerning the DMA transferred information from the second storage section to the first storage section; and loading the DMA transferred descriptor information from the first storage section.

According to the above-described information processing method, when the information is DMA transferred between the first storage section in the information processing system and the second storage section in the information transfer system, it is possible to load the descriptor information without the need to access the second storage section in the information transfer system, which would require a long processing time.

According to yet another embodiment of the present invention, there is provided a program for causing a computer to execute an information processing method to DMA transfer information between a first storage section in an information processing system and a second storage section in an information transfer system. The method includes the steps of: generating descriptor information that indicates a location at which the information is stored in the first storage section and a size of the information; storing the generated descriptor information in the second storage section in the information transfer system; DMA transferring the information between the first storage section and the second storage section based on the descriptor information stored in the second storage section; DMA transferring the descriptor information concerning the DMA transferred information from the second storage section to the first storage section; and loading the DMA transferred descriptor information from the first storage section.

According to yet another embodiment of the present invention, there is provided a computer-readable storage medium that has stored therein a program for causing a computer to execute an information processing method to DMA transfer information between a first storage section in an information processing system and a second storage section in an information transfer system. The method includes the steps of: generating descriptor information that indicates a location at which the information is stored in the first storage section and a size of the information; storing the generated descriptor information in the second storage section in the information transfer system; DMA transferring the information between the first storage section and the second storage section based on the descriptor information stored in the second storage section; DMA transferring the descriptor information concerning the DMA transferred information from the second storage section to the first storage section; and loading the DMA transferred descriptor information from the first storage section.

According to the above-described program and storage medium for the above-described information processing method, when the information is DMA transferred between the first storage section in the information processing system and the second storage section in the information transfer system, the program can be executed by the computer to load the descriptor information without the need to access the second storage section in the information transfer system, which would require a long processing time.

According to yet another embodiment of the present invention, there is provided a DMA controller for DMA transferring information between a first storage section in an information processing system and a second storage section in an information transfer system, the DMA controller including: the second storage section configured to store descriptor information that indicates a location at which the information is stored in the first storage section and a size of the information; and a DMA transfer section configured to DMA transfer the information between the first storage section and the second storage section based on the descriptor information stored in the second storage section, wherein the DMA transfer section DMA transfers the descriptor information concerning the DMA transferred information from the second storage section to the first storage section.

According to the above-described DMA controller, when the information is DMA transferred between the first storage section in the information processing system and the second storage section in the information transfer system, the descriptor information that indicates the location at which the information is stored in the first storage section and the size of the information is stored in the second storage section. Based on the descriptor information stored in the second storage section, the DMA transfer section DMA transfers the information between the first storage section and the second storage section. In this case, the DMA transfer section DMA transfers the descriptor information concerning the DMA transferred information from the second storage section to the first storage section. At this time, the descriptor information which has been DMA transferred by the DMA transfer section can be loaded from the first storage section, without the need to access the second storage section in the information transfer system, which would require a long processing time.

According to yet another embodiment of the present invention, there is provided a DMA transfer method of DMA transferring information between a first storage section in an information processing system and a second storage section in an information transfer system, the method including the steps of: generating descriptor information that indicates a location at which the information is stored in the first storage section and a size of the information; storing the generated descriptor information in the second storage section in the information transfer system; DMA transferring the information between the first storage section and the second storage section based on the descriptor information stored in the second storage section; and DMA transferring the descriptor information concerning the DMA transferred information from the second storage section to the first storage section.

• Provisional Patent
• Utility Patent

• What Is a Patent?
• What Is a Trademark or Servicemark?
• What Is a Copyright?
• Patent Laws